Methods for the production of α,β-unsaturated carboxylic acids and salts thereof

ABSTRACT

Processes for producing an α,β-unsaturated carboxylic acid, such as acrylic acid, or a salt thereof, using solid promoters are disclosed. The solid promoters can be certain solid oxides, mixed oxides, and clays, illustrative examples of which can include alumina, zirconia, magnesia, magnesium aluminate, sepiolite, and similar materials.

BACKGROUND OF THE INVENTION

The majority of industrially synthesized chemical compounds are preparedfrom a limited set of precursors, whose sources are ultimately fossilfuels. It would be beneficial to use a renewable resource, such ascarbon dioxide, which is a non-toxic, abundant, and economical C₁synthetic unit. The coupling of carbon dioxide and olefins holdstremendous promise as one could envision the direct preparation ofacrylates and carboxylic acids through this method. Currently, acrylicacid is produced via a two-stage oxidation of propylene. The productionof acrylic acid directly from carbon dioxide and ethylene wouldrepresent a significant improvement due to the greater availability ofethylene and carbon dioxide versus propylene, the use of a renewablematerial (CO₂) in the synthesis, and the replacement of the two-stepoxygenation process currently being practiced. Accordingly, it is tothese ends that the present invention is directed.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify required oressential features of the claimed subject matter. Nor is this summaryintended to be used to limit the scope of the claimed subject matter.

Processes for producing an α,β-unsaturated carboxylic acid, or a saltthereof, are disclosed herein. These processes represent an improvementover homogeneous processes that result in poor yields and havechallenging separation/isolation procedures, due in part to the reactionbeing conducted in an organic solvent, making isolation of the desiredα,β-unsaturated carboxylic acid (e.g., acrylic acid) difficult. Incontrast, the processes disclosed herein utilize a solid promoter (orsolid activator), providing a heterogeneous system that has a distinctadvantage in ease of separation of the desired product from thecatalytic promoter. Moreover, the solid promoters can result insurprisingly high yields of the desired α,β-unsaturated carboxylic acid,such as acrylic acid.

In accordance with aspects of the present invention, one such processfor producing an α,β-unsaturated carboxylic acid, or a salt thereof, cancomprise:

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter;

(2) forming an adduct of an α,β-unsaturated carboxylic acid adsorbedonto the solid promoter; and

-   -   (3) treating the adduct adsorbed onto the solid promoter to        produce the α,β-unsaturated carboxylic acid, or the salt        thereof.

In another aspect of this invention, a process for producing anα,β-unsaturated carboxylic acid, or a salt thereof, is provided, and inthis aspect, the process can comprise:

(I) contacting

-   -   a transition metal-ligand complex;    -   (ii) an olefin;    -   (iii) carbon dioxide (CO₂);    -   (iv) a diluent; and    -   (v) a solid promoter; and

(II) forming the α,β-unsaturated carboxylic acid, or the salt thereof.

Yet, in another aspect of this invention, a process for performing ametallalactone elimination reaction is provided, and in this aspect, theprocess can comprise:

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter; and

(2) forming an α,β-unsaturated carboxylic acid, or a salt thereof.

In these and other aspects, the processes disclosed herein can be usedto produce, for instance, acrylic acid or a salt thereof.

Both the foregoing summary and the following detailed descriptionprovide examples and are explanatory only. Accordingly, the foregoingsummary and the following detailed description should not be consideredto be restrictive. Further, features or variations may be provided inaddition to those set forth herein. For example, certain aspects andembodiments may be directed to various feature combinations andsub-combinations described in the detailed description.

DEFINITIONS

To define more clearly the terms used herein, the following definitionsare provided. Unless otherwise indicated, the following definitions areapplicable to this disclosure. If a term is used in this disclosure butis not specifically defined herein, the definition from the IUPACCompendium of Chemical Terminology, 2^(nd) Ed (1997) can be applied, aslong as that definition does not conflict with any other disclosure ordefinition applied herein, or render indefinite or non-enabled any claimto which that definition is applied. To the extent that any definitionor usage provided by any document incorporated herein by referenceconflicts with the definition or usage provided herein, the definitionor usage provided herein controls.

While compositions and methods are described in terms of “comprising”various components or steps, the compositions and methods can also“consist essentially of” or “consist of” the various components orsteps, unless stated otherwise.

The terms “a,” “an,” and “the” are intended to include pluralalternatives, e.g., at least one. For instance, the disclosure of “asolid promoter,” “a diluent,” etc., is meant to encompass one, ormixtures or combinations of more than one, solid promoter, diluent,etc., unless otherwise specified.

The term “hydrocarbon” refers to a compound containing only carbon andhydrogen. Other identifiers may be utilized to indicate the presence ofparticular groups in the hydrocarbon, for instance, a halogenatedhydrocarbon indicates the presence of one or more halogen atomsreplacing an equivalent number of hydrogen atoms in the hydrocarbon.

As used herein, the term “α,β-unsaturated carboxylic acid” and itsderivatives refer to a carboxylic acid having a carbon atom of acarbon-carbon double bond attached to the carbonyl carbon atom (thecarbon atom bearing the double bonded oxygen atom). Optionally, theα,β-unsaturated carboxylic acid may contain other functional groupsand/or heteroatoms.

For any particular compound or group disclosed herein, any name orstructure presented is intended to encompass all conformational isomers,regioisomers, stereoisomers, and mixtures thereof that may arise from aparticular set of substituents, unless otherwise specified. The name orstructure also encompasses all enantiomers, diastereomers, and otheroptical isomers (if there are any) whether in enantiomeric or racemicforms, as well as mixtures of stereoisomers, as would be recognized by askilled artisan, unless otherwise specified. For example, a generalreference to pentane includes n-pentane, 2-methyl-butane, and2,2-dimethylpropane; and a general reference to a butyl group includes an-butyl group, a sec-butyl group, an iso-butyl group, and a t-butylgroup.

Various numerical ranges are disclosed herein. When Applicants discloseor claim a range of any type, Applicants' intent is to disclose or claimindividually each possible number that such a range could reasonablyencompass, including end points of the range as well as any sub-rangesand combinations of sub-ranges encompassed therein, unless otherwisespecified. Moreover, all numerical end points of ranges disclosed hereinare approximate. As a representative example, Applicants disclose, in anaspect of the invention, that one or more steps in the processesdisclosed herein can be conducted at a temperature in a range from 10°C. to 75° C. This range should be interpreted as encompassingtemperatures in a range from “about” 10° C. to “about” 75° C.

Applicants reserve the right to proviso out or exclude any individualmembers of any such group, including any sub-ranges or combinations ofsub-ranges within the group, that can be claimed according to a range orin any similar manner, if for any reason Applicants choose to claim lessthan the full measure of the disclosure, for example, to account for areference that Applicants may be unaware of at the time of the filing ofthe application. Further, Applicants reserve the right to proviso out orexclude any individual substituents, analogs, compounds, ligands,structures, or groups thereof, or any members of a claimed group, if forany reason Applicants choose to claim less than the full measure of thedisclosure, for example, to account for a reference that Applicants maybe unaware of at the time of the filing of the application.

The term “substituted” when used to describe a group, for example, whenreferring to a substituted analog of a particular group, is intended todescribe the compound or group wherein any non-hydrogen moiety formallyreplaces hydrogen in that group or compound, and is intended to benon-limiting. A compound or group may also be referred to herein as“unsubstituted” or by equivalent terms such as “non-substituted,” whichrefers to the original group or compound. “Substituted” is intended tobe non-limiting and include inorganic substituents or organicsubstituents as specified and as understood by one of ordinary skill inthe art.

The terms “contact product,” “contacting,” and the like, are used hereinto describe compositions and methods wherein the components arecontacted together in any order, in any manner, and for any length oftime. For example, the components can be contacted by blending ormixing. Further, unless otherwise specified, the contacting of anycomponent can occur in the presence or absence of any other component ofthe compositions and methods described herein. Combining additionalmaterials or components can be done by any suitable method. Further, theterm “contact product” includes mixtures, blends, solutions, slurries,reaction products, and the like, or combinations thereof. Although“contact product” can, and often does, include reaction products, it isnot required for the respective components to react with one another.Similarly, “contacting” two or more components can result in a reactionproduct or a reaction mixture. Consequently, depending upon thecircumstances, a “contact product” can be a mixture, a reaction mixture,or a reaction product.

Although any methods and materials similar or equivalent to thosedescribed herein can be used in the practice or testing of theinvention, the typical methods and materials are herein described.

All publications and patents mentioned herein are incorporated herein byreference for the purpose of describing and disclosing, for example, theconstructs and methodologies that are described in the publications,which might be used in connection with the presently describedinvention. The publications discussed throughout the text are providedsolely for their disclosure prior to the filing date of the presentapplication. Nothing herein is to be construed as an admission that theinventors are not entitled to antedate such disclosure by virtue ofprior invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed generally to methods for formingα,β-unsaturated carboxylic acids, or salts thereof. An illustrativeexample of a suitable α,β-unsaturated carboxylic acid is acrylic acid.

Solid Promoters

Generally, the solid promoter used in the processes disclosed herein cancomprise (or consist essentially of, or consist of) a solid oxide, aclay or pillared clay, or combinations thereof. For instance, it iscontemplated that mixtures or combinations of two or more solidpromoters can be employed in certain aspects of the invention.Generally, the term solid promoter is used interchangeably herein withsolid activator.

In accordance with one aspect, the solid promoter can comprise a basicpromoter, for instance, a solid promoter that can act as a base.Representative and non-limiting examples of basic promoters can includealumina, titania, zirconia, magnesia, boria, calcia, zinc oxide,silica-alumina, silica-coated alumina, silica-titania, silica-zirconia,silica-magnesia, alumina-titania zinc-aluminate, alumina-boria,silica-boria, aluminum phosphate, aluminophosphate,aluminophosphate-silica, magnesium aluminate, titania-zirconia, and thelike, as well as combinations thereof. In accordance with anotheraspect, the solid promoter can comprise a Lewis acid promoter.Representative and non-limiting examples of Lewis acid promoters caninclude silica, alumina, titania, zirconia, magnesia, boria, calcia,zinc oxide, silica-alumina, silica-coated alumina, silica-titania,silica-zirconia, silica-magnesia, alumina-titania, alumina-zirconia,zinc-aluminate, alumina-boria, silica-boria, aluminum phosphate,aluminophosphate, aluminophosphate-silica, magnesium aluminate,titania-zirconia, and the like, as well as combinations thereof. Inaccordance with yet another aspect, the solid promoter can comprise aBronsted base promoter. Representative and non-limiting examples ofBronsted base promoters can include alumina, titania, zirconia,magnesia, boria, calcia, zinc oxide, silica-coated alumina,silica-titania, silica-zirconia, silica-magnesia, alumina-titania,alumina-zirconia, zinc-aluminate, alumina-boria, silica-boria, aluminumphosphate, aluminophosphate, aluminophosphate-silica, magnesiumaluminate, titania-zirconia, and the like, as well as combinationsthereof. In accordance with still another aspect, the solid promoter cancomprise a Bronsted base and Lewis acid promoter. Representative andnon-limiting examples of Bronsted base and Lewis acid promoters caninclude alumina, titania, zirconia, magnesia, boria, calcia, zinc oxide,silica-coated alumina, silica-titania, silica-zirconia, silica-magnesia,alumina-titania, alumina-zirconia, zinc-aluminate, alumina-boria,silica-boria, aluminum phosphate, aluminophosphate,aluminophosphate-silica, magnesium aluminate, titania-zirconia, and thelike, as well as combinations thereof.

Consistent with aspects of this invention, the solid promoter cancomprise (or consist essentially of, or consist of) a solid oxide.Generally, the solid oxide can comprise oxygen and one or more elementsselected from Group 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 ofthe periodic table, or comprise oxygen and one or more elements selectedfrom the lanthanide or actinide elements (See: Hawley's CondensedChemical Dictionary, 11^(th) Ed., John Wiley & Sons, 1995; Cotton, F.A., Wilkinson, G., Murillo, C. A., and Bochmann, M., Advanced InorganicChemistry, 6^(th) Ed., Wiley-Interscience, 1999). For example and notlimited thereto, the solid oxide can comprise oxygen and an element, orelements, selected from Al, B, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, La, Mn,Mo, Ni, Sb, Si, Sn, Sr, Th, Ti, V, W, P, Y, Zn, Zr, Na, K, Cs, Ca, Ba,and Li.

Illustrative examples of solid oxides that can be used as solidpromoters as described herein can include, but are not limited to,Al₂O₃, B₂O₃, BeO, Bi₂O₃, BaO, MgO, CaO, CdO, Ce₂O₃, Co₃O₄, Cr₂O₃, CuO,Fe₂O₃, Ga₂O₃, K₂O, La₂O₃, Mn₂O₃, MoO₃, Na₂O, NiO, P₂O₅, Sb₂O₅, SiO₂,SnO₂, SrO, ThO₂, TiO₂, V₂O₅, WO₃, Y₂O₃, ZnO, ZrO₂, and the like,including mixed oxides thereof, and combinations thereof. In addition tooxides, carbonates and hydroxides of the above elements also can beused, either alone or in combination.

In an aspect, the solid oxide can comprise silica, alumina, titania,zirconia, magnesia, boria, calcia, zinc oxide, silica-alumina,silica-coated alumina, silica-titania, silica-zirconia, silica-magnesia,alumina-titania, alumina-zirconia, zinc-aluminate, alumina-boria,silica-boria, aluminum phosphate, aluminophosphate,aluminophosphate-silica, magnesium aluminate, titania-zirconia, and thelike, or a combination thereof; alternatively, silica; alternatively,alumina; alternatively, titania; alternatively, zirconia; alternatively,magnesia; alternatively, boria; alternatively, calcia; alternatively,zinc oxide; alternatively, silica-alumina; alternatively, silica-coatedalumina; alternatively, silica-titania; alternatively, silica-zirconia;alternatively, silica-magnesia; alternatively, alumina-titania;alternatively, alumina-zirconia; alternatively, zinc-aluminate;alternatively, alumina-boria; alternatively, silica-boria;alternatively, aluminum phosphate; alternatively, aluminophosphate;alternatively, aluminophosphate-silica; alternatively, magnesiumaluminate; or alternatively, titania-zirconia. In another aspect, thesolid oxide can comprise magnesium aluminate, calcium aluminate, zincaluminate, zirconium aluminate, sodium aluminate, magnesium zirconiumoxide, sodium zirconium oxide, calcium zirconium oxide, lanthanumchromium oxide, barium titanium oxide, and the like, or a combinationthereof; alternatively, magnesium aluminate; alternatively, calciumaluminate; alternatively, zinc aluminate; alternatively, zirconiumaluminate; alternatively, sodium aluminate; alternatively, magnesiumzirconium oxide; alternatively, sodium zirconium oxide; alternatively,calcium zirconium oxide; alternatively, lanthanum chromium oxide; oralternatively, barium titanium oxide. Various methods for producingsuitable solid oxides and mixed solid oxides, such as co-gelling, dopingor impregnating are disclosed in, for example, U.S. Pat. Nos. 6,107,230,6,165,929, 6,294,494, 6,300,271, 6,316,553, 6,355,594, 6,376,415,6,388,017, 6,391,816, 6,395,666, 6,524,987, 6,548,441, 6,548,442,6,576,583, 6,613,712, 6,632,894, 6,667,274, 6,750,302, 7,294,599,7,601,665, 7,884,163, and 8,309,485, which are incorporated herein byreference in their entirety. Other suitable processes and procedures forpreparing solid oxides that can be used as solid promoters are wellknown to those of skill in the art.

Consistent with aspects of this invention, the solid promoter cancomprise (or consist essentially of, or consist of) a clay or a pillaredclay. The clay or pillared clay materials that can be employed as asolid promoter in the disclosed processes can encompass clay materialseither in their natural state or that have been treated with variousions by wetting, ion exchange, pillaring, or other processes. In someaspects, the clay or pillared clay material can comprise clays that havebeen ion exchanged with large cations, including polynuclear, highlycharged metal complex cations. In other aspects, the clay or pillaredclay material can comprise clays that have been ion exchanged withsimple salts, including, but not limited to, salts of Al(III), Fe(II),Fe(III), and Zn(II) with ligands such as halide, acetate, sulfate,nitrate, nitrite, and the like.

In another aspect, the clay or pillared clay material can comprise apillared clay. The term “pillared clay” can be used to refer to claymaterials that have been ion exchanged with large, typicallypolynuclear, highly charged metal complex cations. Examples of such ionsinclude, but are not limited to, Keggin ions which can have charges suchas 7+, various polyoxometallates, and other large ions. Thus, the termpillaring generally refers to a simple exchange reaction in which theexchangeable cations of a clay material can be replaced with large,highly charged ions, such as Keggin ions. These polymeric cations arethen immobilized within the interlayers of the clay, and when calcinedcan be converted to metal oxide “pillars,” effectively supporting theclay layers as column-like structures. Thus, once the clay has beendried and calcined to produce the supporting pillars between claylayers, the expanded lattice structure can be maintained and theporosity can be enhanced. The resulting pores can vary in shape and sizeas a function of the pillaring material and the parent clay materialused, among other variables. Examples of pillaring and pillared claysare found in: T. J. Pinnavaia, Science 220 (4595), 365-371 (1983); J. M.Thomas, Intercalation Chemistry, (S. Whittington and A. Jacobson, eds.)Ch. 3, pp. 55-99, Academic Press, Inc., (1972); U.S. Pat. No. 4,452,910;U.S. Pat. No. 5,376,611; and U.S. Pat. No. 4,060,480; the disclosures ofwhich are incorporated herein by reference in their entirety.

In some aspects, the clay or pillared clay can comprise montmorillonite,bentonite, nontronite, hectorite, halloysite, vermiculite, mica,fluoromica, chlorite, sepiolite, attapulgite, palygorskite, illite,saponite, allophone, smectite, kaolinite, pyrophyllite, and the like, orany combination thereof. In other aspects, the clay or pillared clay cancomprise montmorillonite; alternatively, bentonite; alternatively,nontronite; alternatively, hectorite; alternatively, halloysite;alternatively, vermiculite; alternatively, mica; alternatively,fluoromica; alternatively, chlorite; alternatively, sepiolite;alternatively, attapulgite; alternatively, palygorskite; alternatively,illite; alternatively, saponite; alternatively, allophone;alternatively, smectite; alternatively, kaolinite; or alternatively,pyrophyllite.

In accordance with an aspect of this invention, the solid promoter cancomprise silica, alumina, silica-alumina, aluminum phosphate,alumina-boria, silica-magnesia, silica-titania, zirconia, magnesia,magnesium aluminate, sepiolite, titania, palygorskite, montmorillonite,talc, kaolinite, halloysite, pyrophyllite, and the like, as well ascombinations thereof. In accordance with another aspect, the solidpromoter can comprise silica, alumina, silica-alumina, aluminumphosphate, alumina-boria, silica-magnesia, silica-titania, zirconia,magnesia, magnesium aluminate, titania, and the like, as well ascombinations thereof. In accordance with yet another aspect, the solidpromoter can comprise sepiolite, palygorskite, montmorillonite, talc,kaolinite, halloysite, pyrophyllite, and the like, as well ascombinations thereof. In accordance with still another aspect, the solidpromoter can comprise alumina, zirconia, magnesia, magnesium aluminate,sepiolite, and the like, as well as combinations thereof; alternatively,alumina; alternatively, zirconia; alternatively, magnesia;alternatively, magnesium aluminate; or alternatively, sepiolite.

The solid promoters contemplated herein can have any suitable surfacearea, pore volume, and particle size, as would be recognized by those ofskill in the art. For instance, the solid promoter can have a porevolume in a range from 0.1 to 2.5 mL/g, or alternatively, from 0.5 to2.5 mL/g. In a further aspect, the promoter can have a pore volume from1 to 2.5 mL/g. Alternatively, the pore volume can be from 0.1 to 1.0mL/g. Additionally, or alternatively, the solid promoter can have a BETsurface area in a range from 10 to 750 m²/g; alternatively, from 100 to750 m²/g; alternatively, from 100 to 500 m²/g; or alternatively, from 30to 200 m²/g. In a further aspect, the solid promoter can have a surfacearea of from 100 to 400 m²/g, from 200 to 450 m²/g, or from 150 to 350m²/g. The average particle size of the solid promoter can vary greatlydepending upon the process specifics, however, average particle sizes inthe range of from 5 to 500 microns, from 10 to 250 microns, or from 25to 200 microns, are often employed. Alternatively, ⅛ inch to ¼ inchpellets or beads can be used.

Prior to use, these solid promoters can be calcined. The calcining stepcan be conducted at a variety of temperatures and time periods, and in avariety of atmospheres (an inert atmosphere, an oxidizing atmosphere, areducing atmosphere). For instance, the calcining step can be conductedat a peak calcining temperature in a range from 150° C. to 1000° C.;alternatively, from 250° C. to 1000° C.; alternatively, from 250° C. to950° C.; alternatively, from 250° C. to 750° C.; alternatively, from400° C. to 700° C.; alternatively, from 300° C. to 650° C.; oralternatively, from 400° C. to 600° C. In these and other aspects, thesetemperature ranges also are meant to encompass circumstances where thecalcining step is conducted at a series of different temperatures (e.g.,an initial calcining temperature, a peak calcining temperature), insteadof at a single fixed temperature, falling within the respective ranges.For instance, the calcining step can start at an initial calciningtemperature, and subsequently, the temperature of the calcining step canbe increased to the peak calcining temperature, for example, a peakcalcining temperature in a range from 500° C. to 1000° C., or from 250°C. to 750° C.

The duration of the calcining step is not limited to any particularperiod of time. Hence, the calcining step can be conducted, for example,in a time period ranging from as little as 15-45 minutes to as long as12-24 hours, or more. The appropriate calcining time can depend upon,for example, the initial/peak calcining temperature, and the atmosphereunder which calcining is conducted, among other variables. Generally,however, the calcining step can be conducted in a time period that canbe in a range from 45 minutes to 18 hours, such as, for example, from 45minutes to 15 hours, from 1 hour to 12 hours, from 2 hours to 10 hours,from 3 hours to 10 hours, or from 4 hours to 10 hours.

Diluents

The processes disclosed herein typically are conducted in the presenceof a diluent. Mixtures and/or combinations of diluents can be utilizedin these processes. The diluent can comprise, consist essentially of, orconsist of, any suitable solvent or any solvent disclosed herein, unlessotherwise specified. For instance, in accordance with one aspect of thisinvention, the diluent can comprise a non-protic solvent. Representativeand non-limiting examples of non-protic solvents can includetetrahydrofuran (THF), 2,5-Me₂THF, acetone, toluene, chlorobenzene,pyridine, carbon dioxide, and the like, as well as combinations thereof.In accordance with another aspect, the diluent can comprise a weaklycoordinating or non-coordinating solvent. Representative andnon-limiting examples of weakly coordinating or non-coordinatingsolvents can include toluene, chlorobenzene, paraffins, halogenatedparaffins, and the like, as well as combinations thereof. In accordancewith yet another aspect, the diluent can comprise a carbonyl-containingsolvent, for instance, ketones, esters, amides, and the like, as well ascombinations thereof. Representative and non-limiting examples ofcarbonyl-containing solvents can include acetone, ethyl methyl ketone,ethyl acetate, propyl acetate, butyl acetate, isobutyl isobutyrate,methyl lactate, ethyl lactate, N,N-dimethylformamide, and the like, aswell as combinations thereof. In still another aspect, the diluent cancomprise THF, 2,5-Me₂THF, methanol, acetone, toluene, chlorobenzene,pyridine, or a combination thereof; alternatively, THF; alternatively,2,5-Me₂THF; alternatively, methanol; alternatively, acetone;alternatively, toluene; alternatively, chlorobenzene; or alternatively,pyridine.

In an aspect, the diluent can comprise (or consist essentially of, orconsist of) an aromatic hydrocarbon solvent. Non-limiting examples ofsuitable aromatic hydrocarbon solvents that can be utilized singly or inany combination include benzene, toluene, xylene (inclusive ofortho-xylene, meta-xylene, para-xylene, or mixtures thereof), andethylbenzene, or combinations thereof; alternatively, benzene;alternatively, toluene; alternatively, xylene; or alternatively,ethylbenzene.

In an aspect, the diluent can comprise (or consist essentially of, orconsist of) a halogenated aromatic hydrocarbon solvent. Non-limitingexamples of suitable halogenated aromatic hydrocarbon solvents that canbe utilized singly or in any combination include chlorobenzene,dichlorobenzene, and combinations thereof; alternatively, chlorobenzene;or alternatively, dichlorobenzene.

In an aspect, the diluent can comprise (or consist essentially of, orconsist of) an ether solvent. Non-limiting examples of suitable ethersolvents that can be utilized singly or in any combination includedimethyl ether, diethyl ether, diisopropyl ether, di-n-propyl ether,di-n-butyl ether, diphenyl ether, methyl ethyl ether, methyl t-butylether, dihydrofuran, tetrahydrofuran (THF), 2,5-Me₂THF,1,2-dimethoxyethane, 1,4-dioxane, and combinations thereof;alternatively, diethyl ether, dibutyl ether, THF, 2,5-Me₂THF,1,2-dimethoxyethane, 1,4-dioxane, and combinations thereof;alternatively, THF; or alternatively, diethyl ether.

Metallalactones and Transition Metal-Ligand Complexes

Generally, the processes disclosed herein employ a metallalactone or atransition metal-ligand complex. The transition metal of themetallalactone, or of the transition metal-ligand complex, can be aGroup 3 to Group 8 transition metal or, alternatively, a Group 8 toGroup 11 transition metal. In one aspect, for instance, the transitionmetal can be Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, or Au, while inanother aspect, the transition metal can be Fe, Ni, or Rh.Alternatively, the transition metal can be Fe; alternatively, thetransition metal can be Co; alternatively, the transition metal can beNi; alternatively, the transition metal can be Cu; alternatively, thetransition metal can be Ru; alternatively, the transition metal can beRh; alternatively, the transition metal can be Pd; alternatively, thetransition metal can be Ag; alternatively, the transition metal can beIr; alternatively, the transition metal can be Pt; or alternatively, thetransition metal can Au.

In particular aspects contemplated herein, the transition metal can beNi. Hence, the metallalactone can be a nickelalactone and the transitionmetal-ligand complex can be a Ni-ligand complex in these aspects.

The ligand of the metallalactone, or of the transition metal-ligandcomplex, can be any suitable neutral electron donor group and/or Lewisbase. For instance, the suitable neutral ligands can include sigma-donorsolvents that contain a coordinating atom (or atoms) that can coordinateto the transition metal of the metallalactone (or of the transitionmetal-ligand complex). Examples of suitable coordinating atoms in theligands can include, but are not limited to, O, N, S, and P, orcombinations of these atoms. In some aspects consistent with thisinvention, the ligand can be a bidentate ligand.

In an aspect, the ligand used to form the metallalactone or thetransition metal-ligand complex can be an ether, an organic carbonyl, athioether, an amine, a nitrile, or a phosphine. In another aspect, theligand used to form the metallalactone or the transition metal-ligandcomplex can be an acyclic ether, a cyclic ether, an acyclic organiccarbonyl, a cyclic organic carbonyl, an acyclic thioether, a cyclicthioether, a nitrile, an acyclic amine, a cyclic amine, an acyclicphosphine, or a cyclic phosphine.

Suitable ethers can include, but are not limited to, dimethyl ether,diethyl ether, dipropyl ether, dibutyl ether, methyl ethyl ether, methylpropyl ether, methyl butyl ether, diphenyl ether, ditolyl ether,tetrahydrofuran, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran,2,3-dihydrofuran, 2,5-dihydrofuran, furan, benzofuran, isobenzofuran,dibenzofuran, tetrahydropyran, 3,4-dihydro-2H-pyran,3,6-dihydro-2H-pyran, 2H-pyran, 4H-pyran, 1,3-dioxane, 1,4-dioxane,morpholine, and the like, including substituted derivatives thereof.

Suitable organic carbonyls can include ketones, aldehydes, esters, andamides, either alone or in combination, and illustrative examples caninclude, but are not limited to, acetone, acetophonone, benzophenone,N,N-dimethylformamide, N,N-dimethylacetamide, methyl acetate, ethylacetate, and the like, including substituted derivatives thereof.

Suitable thioethers can include, but are not limited to, dimethylthioether, diethyl thioether, dipropyl thioether, dibutyl thioether,methyl ethyl thioether, methyl propyl thioether, methyl butyl thioether,diphenyl thioether, ditolyl thioether, thiophene, benzothiophene,tetrahydrothiophene, thiane, and the like, including substitutedderivatives thereof.

Suitable nitriles can include, but are not limited to, acetonitrile,propionitrile, butyronitrile, benzonitrile, 4-methylbenzonitrile, andthe like, including substituted derivatives thereof.

Suitable amines can include, but are not limited to, methyl amine, ethylamine, propyl amine, butyl amine, dimethyl amine, diethyl amine,dipropyl amine, dibutyl amine, trimethyl amine, triethyl amine,tripropyl amine, tributyl amine, aniline, diphenylamine, triphenylamine,tolylamine, xylylamine, ditolylamine, pyridine, quinoline, pyrrole,indole, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine,2,5-dimethylpyrrole, 2,5-diethylpyrrole, 2,5-dipropylpyrrole,2,5-dibutylpyrrole, 2,4-dimethylpyrrole, 2,4-diethylpyrrole,2,4-dipropylpyrrole, 2,4-dibutylpyrrole, 3,4-dimethylpyrrole,3,4-diethylpyrrole, 3,4-dipropylpyrrole, 3,4-dibutylpyrrole,2-methylpyrrole, 2-ethylpyrrole, 2-propylpyrrole, 2-butylpyrrole,3-methylpyrrole, 3-ethylpyrrole, 3-propylpyrrole, 3-butylpyrrole,3-ethyl-2,4-dimethylpyrrole, 2,3,4,5-tetramethylpyrrole,2,3,4,5-tetraethylpyrrole, 2,2′-bipyridine,1,8-diazabicyclo[5.4.0]undec-7-ene, di(2-pyridyl)dimethylsilane,N,N,N′,N′-tetramethylethylenediamine, 1,10-phenanthroline,2,9-dimethyl-1,10-phenanthroline, glyoxal-bis(mesityl)-1,2-diimine andthe like, including substituted derivatives thereof. Suitable amines canbe primary amines, secondary amines, or tertiary amines.

Suitable phosphines and other phosphorus compounds can include, but arenot limited to, trimethylphosphine, triethylphosphine,tripropylphosphine, tributylphosphine, phenylphosphine, tolylphosphine,diphenylphosphine, ditolylphosphine, triphenylphosphine,tritolylphosphine, methyldiphenylphosphine, dimethylphenylphosphine,ethyldiphenylphosphine, diethylphenylphosphine, tricyclohexylphosphine,trimethyl phosphite, triethyl phosphite, tripropyl phosphite,triisopropyl phosphite, tributyl phosphite and tricyclohexyl phosphite,2-(di-t-butylphosphino)biphenyl, 2-di-t-butylphosphino-1,1′-binaphthyl,2-(di-t-butylphosphino)-3,6-dimethoxy-2′,4′,6′-tri-i-propyl-1,1′-biphenyl,2-di-t-butylphosphino-2′-methylbiphenyl,2-(di-t-butylphosphinomethyl)pyridine,2-di-t-butylphosphino-2′,4′,6′-tri-i-propyl-1,1′-biphenyl,2-(dicyclohexylphosphino)biphenyl,(S)-(+)-(3,5-dioxa-4-phospha-cyclohepta[2,1-a;3,4-a′]dinaphthalen-4-yl)dimethylamine,2-(diphenylphosphino)-2′-methoxy-1,1′-binaphthyl,1,2,3,4,5-pentaphenyl-1′-(di-t-butylphosphino) ferrocene,2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP),1,2-bis(dimethylphosphino)ethane, 1,2-bis(diethylphosphino)ethane,1,2-bis(dipropylphosphino)-ethane, 1,2-bis(diisopropylphosphino)ethane,1,2-bis(dibutyl-phosphino)ethane, 1,2-bis(di-t-butyl-phosphino)ethane,1,2-bis(dicyclohexylphosphino)ethane,1,3-bis(dicyclohexylphosphino)propane,1,3-bis(diisopropylphosphino)propane, 1,3-bis(diphenylphosphino)propane,1,3-bis(di-t-butylphosphino)propane,1,4-bis(diisopropylphosphino)butane, 1,4-bis(diphenylphosphino)butane,2,2′-bis[bis(3,5-dimethylphenyl)phosphino]-4,4′,6,6′-tetramethoxybiphenyl,2,6-bis(di-t-butylphosphinomethyl)pyridine,2,2′-bis(dicyclohexylphosphino)-1,1′-biphenyl,bis(2-dicyclohexylphosphinophenyl)ether,5,5′-bis(diphenylphosphino)-4,4′-bi-1,3-benzodioxole,2-t-butylphosphinomethylpyridine, bis(diphenylphosphino)ferrocene,bis(diphenylphosphino)methane, bis(dicyclohexylphosphino)methane,bis(di-t-butylphosphino)methane, and the like, including substitutedderivatives thereof.

In other aspects, the ligand used to form the metallalactone or thetransition metal-ligand complex can be a carbene, for example, aN-heterocyclic carbene (NHC) compound. Representative and non-limitingexamples of suitable N-heterocyclic carbene (NHC) materials include thefollowing:

Illustrative and non-limiting examples of metallalactone complexes(representative nickelalactones) suitable for use as described hereininclude the following compounds (Cy=cyclohexyl, ^(t)Bu=tert-butyl):

The transition metal-ligand complexes corresponding to theseillustrative metallalactones are shown below:

Metallalactones can be synthesized according to the following generalreaction scheme (illustrated with nickel as the transition metal;Ni(COD)₂ is bis(1,5-cyclooctadiene)nickel(0)):

and according to suitable procedures well known to those of skill in theart.

Suitable ligands, transition metal-ligand complexes, and metallalactonesare not limited solely to those ligands, transition metal-ligandcomplexes, and metallalactones disclosed herein. Other suitable ligands,transition metal-ligand complexes, and/or metallalactones are described,for example, in U.S. Pat. Nos. 7,250,510, 8,642,803, and 8,697,909;Journal of Organometallic Chemistry, 1983, 251, C51-053; Z. Anorg. Allg.Chem., 1989, 577, 111-114; Journal of Organometallic Chemistry, 2004,689, 2952-2962; Organometallics, 2004, Vol. 23, 5252-5259; Chem. Commun,2006, 2510-2512; Organometallics, 2010, Vol. 29, 2199-2202; Chem. Eur.J., 2012, 18, 14017-14025; Organometallics, 2013, 32 (7), 2152-2159; andChem. Eur. J., 2014, Vol. 20, 11, 3205-3211; the disclosures of whichare incorporated herein by reference in their entirety.

Producing α,β-Unsaturated Carboxylic Acids and Salts Thereof

Generally, the features of the processes disclosed herein (e.g., themetallalactone, the diluent, the solid promoter, the α,β-unsaturatedcarboxylic acid or salt thereof, the transition metal-ligand complex,the olefin, and the conditions under which the α,β-unsaturatedcarboxylic acid, or a salt thereof, is formed, among others) areindependently described, and these features may be combined in anycombination to further describe the disclosed processes.

In accordance with an aspect of the present invention, a process forperforming a metallalactone elimination reaction is disclosed. Thisprocess can comprise (or consist essentially of, or consist of):

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter; and

(2) forming an α,β-unsaturated carboxylic acid, or a salt thereof.

Suitable metallalactones, diluents, and solid promoters are disclosedhereinabove. In this process for performing a metallalactone eliminationreaction, for instance, at least a portion of the diluent can comprisethe α,β-unsaturated carboxylic acid, or the salt thereof, that is formedin step (2) of this process.

In accordance with another aspect of the present invention, a processfor producing an α,β-unsaturated carboxylic acid, or a salt thereof, isdisclosed. This process can comprise (or consist essentially of, orconsist of):

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter;

(2) forming an adduct of an α,β-unsaturated carboxylic acid adsorbedonto the solid promoter; and

(3) treating the adduct adsorbed onto the solid promoter to produce theα,β-unsaturated carboxylic acid, or the salt thereof.

In this process for producing an α,β-unsaturated carboxylic acid or asalt thereof, for instance, at least a portion of the diluent comprisinga transition metal of the metallalactone can be removed after step (2),and before step (3), of this process. Suitable metallalactones,diluents, and solid promoters are disclosed hereinabove.

In some aspects, the contacting step—step (1)—of these processes caninclude contacting, in any order, the metallalactone, the diluent, andthe solid promoter, and additional unrecited materials. In otheraspects, the contacting step can consist essentially of, or consist of,the metallalactone, the diluent, and the solid promoter components.Likewise, additional materials or features can be employed in theforming step—step (2)—of these processes, and/or in the treatingstep—step (3)—of the process for producing the α,β-unsaturatedcarboxylic acid, or the salt thereof. Further, it is contemplated thatthese processes for performing a metallalactone elimination reaction andfor producing an α,β-unsaturated carboxylic acid, or a salt thereof, canemploy more than one metallalactone and/or more than one solid promoter.Additionally, a mixture or combination of two or more diluents can beemployed.

Any suitable reactor, vessel, or container can be used to contact themetallalactone, diluent, and solid promoter, non-limiting examples ofwhich can include a flow reactor, a continuous reactor, a fixed bedreactor, and a stirred tank reactor, including more than one reactor inseries or in parallel, and including any combination of reactor typesand arrangements. In particular aspects consistent with this invention,the metallalactone and the diluent contact a fixed bed of the solidpromoter, for instance, in a suitable vessel, such as in a continuousfixed bed reactor. In further aspects, combinations of more than onesolid promoter can be used, such as a mixed bed of a first solidpromoter and a second solid promoter, or sequential beds of a firstsolid promoter and a second solid promoter. In these and other aspects,the feed stream can flow upward or downward through the fixed bed. Forinstance, the metallalactone and the diluent can contact the first solidpromoter and then the second solid promoter in a downward floworientation, and the reverse in an upward flow orientation. In adifferent aspect, the metallalactone and the solid promoter can becontacted by mixing or stirring in the diluent, for instance, in asuitable vessel, such as a stirred tank reactor.

Step (2) of the process for producing an α,β-unsaturated carboxylicacid, or a salt thereof, recites forming an adduct of theα,β-unsaturated carboxylic acid adsorbed onto the solid promoter. Thisadduct can contain all or a portion of the α,β-unsaturated carboxylicacid, and is inclusive of salts of the α,β-unsaturated carboxylic acid.

In step (3) of the process for producing an α,β-unsaturated carboxylicacid or a salt thereof, the adduct adsorbed onto the solid promoter istreated to produce the α,β-unsaturated carboxylic acid, or the saltthereof. Various methods can be used to liberate or desorb theα,β-unsaturated carboxylic acid, or the salt thereof, from the solidpromoter. In one aspect, for instance, the treating step can comprisecontacting the adduct adsorbed onto the solid promoter with an acid.Representative and non-limiting examples of suitable acids can includeHCl, acetic acid, and the like, as well as combinations thereof. Inanother aspect, the treating step can comprise contacting the adductadsorbed onto the solid promoter with a base. Representative andnon-limiting examples of suitable bases can include carbonates (e.g.,Na₂CO₃, Cs₂CO₃, MgCO₃), hydroxides (e.g., Mg(OH)₂, Na(OH), alkoxides(e.g., Al(O^(i)Pr)₃, Na(O^(t)Bu), Mg(OEt)₂), and the like, as well ascombinations thereof (^(i)Pr=isopropyl, ^(t)Bu=tert-butyl, Et=ethyl). Inyet another aspect, the treating step can comprise contacting the adductadsorbed onto the solid promoter with a suitable solvent. Representativeand non-limiting examples of suitable solvents can includecarbonyl-containing solvents such as ketones, esters, amides, etc.(e.g., acetone, ethyl acetate, N,N-dimethylformamide, etc., as describedherein above), alcohol solvents, water, and the like, as well ascombinations thereof. In still another aspect, the treating step cancomprise heating the adduct adsorbed onto the solid promoter to anysuitable temperature. This temperature can be in a range, for example,from 50 to 1000° C., from 100 to 800° C., from 150 to 600° C., from 250to 1000° C., from 250° C. to 550° C., or from 150° C. to 500° C. Theduration of this heating step is not limited to any particular period oftime, as long of the period of time is sufficient to liberate theα,β-unsaturated carboxylic acid from the solid promoter. As those ofskill in the art recognize, the appropriate treating step depends uponseveral factors, such as the particular diluent used in the process, andthe particular solid promoter used in the process, amongst otherconsiderations.

In these processes for performing a metallalactone elimination reactionand for producing an α,β-unsaturated carboxylic acid (or a saltthereof), additional process steps can be conducted before, during,and/or after any of the steps described herein. As an example, theseprocesses can further comprise a step (e.g., prior to step (1)) ofcontacting a transition metal-ligand complex with an olefin and carbondioxide (CO₂) to form the metallalactone. Transition metal-ligandcomplexes are described hereinabove. Illustrative and non-limitingexamples of suitable olefins can include ethylene, propylene, butene(e.g., 1-butene), pentene, hexene (e.g., 1-hexene), heptane, octene(e.g., 1-octene), and the like, as well as combinations thereof.

Yet, in accordance with another aspect of the present invention, aprocess for producing an α,β-unsaturated carboxylic acid, or a saltthereof, is disclosed. This process can comprise (or consist essentiallyof, or consist of):

(I) contacting

-   -   (i) a transition metal-ligand complex;    -   (ii) an olefin;    -   (iii) carbon dioxide (CO₂);    -   (iv) a diluent; and    -   (v) a solid promoter; and

(II) forming the α,β-unsaturated carboxylic acid, or the salt thereof.

Suitable transition metal-ligands, olefins, diluents, and solidpromoters are disclosed hereinabove. In some aspects, the contactingstep—step (1)—of this process can include contacting, in any order, thetransition metal-ligand, the olefin, the diluent, the solid promoter,and carbon dioxide, and additional unrecited materials. In otheraspects, the contacting step can consist essentially of, or consist of,contacting, in any order, the transition metal-ligand, the olefin, thediluent, the solid promoter, and carbon dioxide. Likewise, additionalmaterials or features can be employed in the forming step—step (2)—ofthis process. Further, it is contemplated that this processes forproducing an α,β-unsaturated carboxylic acid, or a salt thereof, canemploy more than one transition metal-ligand complex and/or more thanone solid promoter and/or more than one olefin. Additionally, a mixtureor combination of two or more diluents can be employed. As above, anysuitable reactor, vessel, or container can be used to contact thetransition metal-ligand, olefin, diluent, solid promoter, and carbondioxide, whether using a fixed bed of the solid promoter, a stirred tankfor contacting (or mixing), or some other reactor configuration andprocess. While not wishing to be bound by the following theory, aproposed and illustrative reaction scheme for this process is providedbelow:

Independently, the contacting and forming steps of any of the processesdisclosed herein (i.e., for performing a metallalactone eliminationreaction, for producing an α,β-unsaturated carboxylic acid, or a saltthereof), can be conducted at a variety of temperatures, pressures, andtime periods. For instance, the temperature at which the components instep (1) or step (I) are initially contacted can be the same as, ordifferent from, the temperature at which the forming step is performed.As an illustrative example, in the contacting step, the components canbe contacted initially at temperature T1 and, after this initialcombining, the temperature can be increased to a temperature T2 for theforming step (e.g., to form the α,β-unsaturated carboxylic acid, or thesalt thereof). Likewise, the pressure can be different in the contactingstep and the forming step. Often, the time period in the contacting stepcan be referred to as the contact time, while the time period in formingstep can be referred to as the reaction time. The contact time and thereaction time can be, and often are, different.

In an aspect, the contacting step and/or the forming step of theprocesses disclosed herein can be conducted at a temperature in a rangefrom 0° C. to 250° C.; alternatively, from 20° C. to 200° C.;alternatively, from 0° C. to 95° C.; alternatively, from 10° C. to 75°C.; alternatively, from 10° C. to 50° C.; or alternatively, from 15° C.to 70° C. In these and other aspects, after the initial contacting, thetemperature can be changed, if desired, to another temperature for theforming step. These temperature ranges also are meant to encompasscircumstances where the contacting step and/or the forming step can beconducted at a series of different temperatures, instead of at a singlefixed temperature, falling within the respective ranges.

In an aspect, the contacting step and/or the forming step of theprocesses disclosed herein can be conducted at a pressure in a rangefrom 5 to 10,000 psig, such as, for example, from 5 to 2500 psig. Insome aspects, the pressure can be in a range from 5 to 500 psig;alternatively, from 25 to 3000 psig; alternatively, from 45 to 1000psig; or alternatively, from 50 to 250 psig.

The contacting step of the processes is not limited to any particularduration of time. That is, the respective components can be initiallycontacted rapidly, or over a longer period of time, before commencingthe forming step. Hence, the contacting step can be conducted, forexample, in a time period ranging from as little as 1-30 seconds to aslong as 1-12 hours, or more. In non-continuous or batch operations, theappropriate reaction time for the forming step can depend upon, forexample, the reaction temperature, the reaction pressure, and the ratiosof the respective components in the contacting step, among othervariables. Generally, however, the forming step can occur over a timeperiod that can be in a range from 1 minute to 96 hours, such as, forexample, from 2 minutes to 96 hours, from 5 minutes to 72 hours, from 10minutes to 72 hours, or from 15 minutes to 48 hours.

If the process employed is a continuous process, then themetallalactone/solid promoter catalyst contact/reaction time (or thetransition metal-ligand/solid promoter catalyst contact/reaction time)can be expressed in terms of weight hourly space velocity (WHSV)—theratio of the weight of the metallalactone (or transition metal-ligandcomplex) which comes in contact with a given weight of solid promoterper unit time. While not limited thereto, the WHSV employed, based onthe amount of the solid promoter, can be in a range from 0.05 to 100,from 0.05 to 50, from 0.075 to 50, from 0.1 to 25, from 0.5 to 10, from1 to 25, or from 1 to 5.

In the processes disclosed herein, the molar yield of theα,β-unsaturated carboxylic acid, or the salt thereof), based on themetallalactone (or the transition metal-ligand complex) is at least 2%,and more often can be at least 5%, at least 10%, or at least 15%. Inparticular aspects of this invention, the molar yield can be at least18%, at least 20%, at least 25%, at least 35%, at least 50%, at least60%, at least 75%, or at least 85%, and often can range up to 90%, or95%, or 100%.

The specific α,β-unsaturated carboxylic acid (or salt thereof) that canbe formed or produced using the processes of this invention is notparticularly limited. Illustrative and non-limiting examples of theα,β-unsaturated carboxylic acid can include acrylic acid, methacrylicacid, 2-ethylacrylic acid, and the like, as well as combinationsthereof. Illustrative and non-limiting examples of the salt of theα,β-unsaturated carboxylic acid can include sodium acrylate, magnesiumacrylate, sodium methacrylate, and the like, as well as combinationsthereof.

Once formed, the α,β-unsaturated carboxylic acid (or salt thereof) canbe purified and/or isolated and/or separated using suitable techniqueswhich can include, but are not limited to, evaporation, distillation,chromatography, crystallization, extraction, washing, decanting,filtering, drying, and the like, including combinations of more than oneof these techniques. In an aspect, the process can for performing ametallalactone elimination reaction (or the process for producing anα,β-unsaturated carboxylic acid, or a salt thereof) can further comprisea step of separating or isolating the α,β-unsaturated carboxylic acid(or salt thereof) from other components, e.g., the diluent, the solidpromoter, etc.

EXAMPLES

The invention is further illustrated by the following examples, whichare not to be construed in any way as imposing limitations to the scopeof this invention. Various other aspects, embodiments, modifications,and equivalents thereof which, after reading the description herein, maysuggest themselves to one of ordinary skill in the art without departingfrom the spirit of the present invention or the scope of the appendedclaims.

The following nickelalactone complexes, which can be derived fromCO₂—ethylene coupling, were used to evaluate various homogeneous andheterogeneous (solid) promoters in the examples that follow.

The general nickelalactone elimination reaction was performed asfollows. A flask was charged with 10 mg of nickelalactone (A, B, or C),promoter, and approximately 10 mL of diluent. The reaction mixture washeated with vigorous stirring on an oil bath under conditions describedin the examples below. The reaction mixture was allowed to cool toambient temperature, then acidified. The yield of acrylic acid wasdetermined by ¹H NMR in D₆-acetone versus an internal standard sorbicacid stock solution.

Examples 1-8 Evaluation of Homogeneous Activators/Promoters AcrylateElimination

For Examples 1-8, 5 equivalents of the activator/promoter (per Ni) wereincubated with the nickelalactone (A, B, or C) at 50° C. for 3 hours,followed by eventual acid hydrolysis and extraction to quantify theamount of acrylic acid by ¹H NMR against an internal standard, asreflected in the following reaction scheme:

The results of the evaluation of the homogeneous activators/promotersare summarized in Table I. The diluents employed in Example 1 andExamples 2-7 were 5:1 tetrahydrofuran/acetone and tetrahydrofuran,respectively. Example 8 was investigated in tetrahydrofuran, methanol,and acetone. The homogeneous promoter of Example 5 was a solution ofmethylaluminoxane in toluene, while the homogeneous promoter of Example6 was a mixture of Mg(^(n)Bu)₂ and methanol, which results in analkoxide. As shown in Table I, the homogeneous activators/promoters ofExamples 1-8 failed to yield any acrylic acid with any of thenickelalactones investigated.

TABLE I Molar Yields of Examples 1-8. Example Promoter A B C 1 Na₂(CO₃)0 0 0 2 Al(CH₂CH₃)₃ 0 0 0 3 Al(OCH₂CH₃)₃ 0 0 0 4 Ti(O^(i)Pr)₄ 0 — — 5(Al(CH₃)O)_(n) 0 — — 6 Mg(^(n)Bu)₂ + MeOH 0 — — 7 Ca(OMe)₂ 0 — — 8Mg(OH)₂ 0 — — Notes: Me = methyl; ^(i)Pr = isopropyl; ^(n)Bu = n-butyl.

Examples 9-12 Evaluation of Solid/Heterogeneous Activators/PromotersAcrylate Elimination

Examples 9-12 were performed in a manner similar to that of Examples2-7, as reflected in the following reaction scheme (25 equivalents perNi were based on site concentration (mmol/g) of the solidactivator/promoter; HCl was used to liberate the acrylic acid foranalysis):

The results of the evaluation of the solid/heterogeneousactivators/promoters (calcined at 400° C.) are summarized in Table II.Unexpectedly, in contrast with the homogeneous Al and Mg promoters ofExamples 2-3, 5-6, and 8, the solid promoters of Examples 9-12 produceda measurable amount of acrylic acid. More surprisingly, Example 11A and11C (zirconia) and Example 12A and 12C (magnesia) provided significantmolar yields of acrylic acid (from 20% to 90%).

TABLE II Molar Yields of Examples 9-12. Site conc. Example Promoter(mmol/g) A B C 9 alumina 5.4  0 0 11 10 silica-magnesia 5.3 Trace 0 0 11zirconia 1.3 23 0 23 12 magnesia 1.1 88 6 58

Examples 13-24 Evaluation of Solid/Heterogeneous Activators/PromotersAcrylate Elimination

Examples 13-24 were performed in a manner similar to that of Examples9-12, with only nickelatactone A, as reflected in the following reactionscheme (25 equivalents per Ni were based on site concentration (mmol/g)of the solid activator/promoter; HCl was used to liberate the acrylicacid for analysis):

The results of the evaluation of the solid/heterogeneousactivators/promoters (calcined at 400° C.) in differentdiluents/solvents are summarized in Table III. Unexpectedly, alumina,zirconia, magnesia, magnesium aluminate, and sepiolite producedsignificant amounts of acrylic acid using different diluents, withgenerally from 5% to 90% molar yield.

Magnesium aluminate was further tested under different calciningconditions. At 400° C. in THF diluent, the yield was 37%. Calcining at250° C. reduced the yield to 6%, while calcining at 550° C. increasedthe yield to 47%.

TABLE III Molar Yields of Examples 13-24. Site conc. Example Promoter(mmol/g) THF 2,5-Me₂THF Methanol Acetone Toluene Chlorobenzene 13 silica1.0 0 — — 0 0 0 14 alumina 5.4 10 — 0 12 12 38 15 silica-alumina 5.0 4 —— 0 0 0 16 aluminum phosphate 4.0 0 — — 0 0 0 17 alumina-boria 5.4 trace— — 0 0 trace 18 silica-magnesia 5.3 trace — 0 trace 0 0 19silica-titania 5.4 6 — — 0 0 0 20 zirconia 1.3 23 — 0 5 0 — 21 magnesia1.1 88 27 0 33 18 45 22 magnesium aluminate 1.1 37 30 — — 43 41 23sepiolite 2.2 17 — — 0 trace 12 24 titania 1.4 0 — — 0 0 0

The invention is described above with reference to numerous aspects andembodiments, and specific examples. Many variations will suggestthemselves to those skilled in the art in light of the above detaileddescription. All such obvious variations are within the full intendedscope of the appended claims. Other embodiments of the invention caninclude, but are not limited to, the following (embodiments typicallyare described as “comprising” but, alternatively, can “consistessentially of” or “consist of” unless specifically stated otherwise):

Embodiment 1

A process for performing a metallalactone elimination reaction, theprocess comprising:

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter; and

(2) forming an α,β-unsaturated carboxylic acid, or a salt thereof.

Embodiment 2

The process defined in embodiment 1, wherein at least a portion of thediluent comprises the α,β-unsaturated carboxylic acid, or the saltthereof, formed in step (2).

Embodiment 3

A process for producing an α,β-unsaturated carboxylic acid, or a saltthereof, the process comprising:

(1) contacting

-   -   (a) a metallalactone;    -   (b) a diluent; and    -   (c) a solid promoter;    -   (2) forming an adduct of an α,β-unsaturated carboxylic acid        adsorbed onto the solid promoter; and    -   (3) treating the adduct adsorbed onto the solid promoter to        produce the α,β-unsaturated carboxylic acid, or the salt        thereof.

Embodiment 4

The process defined in embodiment 3, wherein at least a portion of thediluent comprising a transition metal of the metallalactone is removedafter step (2).

Embodiment 5

The process defined in any one of embodiments 1-4, wherein in step (1),the metallalactone and the diluent contact a fixed bed of the solidpromoter.

Embodiment 6

The process defined in any one of embodiments 1-4, wherein in step (1),the metallalactone and the solid promoter are contacted bymixing/stirring in the diluent.

Embodiment 7

The process defined in any one of embodiments 3-6, wherein the treatingstep comprises contacting the adduct adsorbed onto the solid promoterwith any suitable acid, or any acid disclosed herein, e.g., HCl, aceticacid, etc.

Embodiment 8

The process defined in any one of embodiments 3-6, wherein the treatingstep comprises contacting the adduct adsorbed onto the solid promoterwith any suitable base, or any base disclosed herein, e.g., carbonates(e.g., Na₂CO₃, Cs₂CO₃, MgCO₃), hydroxides (e.g., Mg(OH)₂, NaOH),alkoxides (e.g., Al(O^(i)Pr)₃, Na(O^(t)Bu), Mg(OEt)₂), etc.

Embodiment 9

The process defined in any one of embodiments 3-6, wherein the treatingstep comprises contacting the adduct adsorbed onto the solid promoterwith any suitable solvent, or any solvent disclosed herein, e.g.,carbonyl-containing solvents such as ketones, esters, amides, etc.(e.g., acetone, ethyl acetate, N,N-dimethylformamide), alcohol solvents,water, etc.

Embodiment 10

The process defined in any one of embodiments 3-6, wherein the treatingstep comprises heating the adduct adsorbed onto the solid promoter toany suitable temperature, or a temperature in any range disclosedherein, e.g., from 50 to 1000° C., from 100 to 800° C., from 150 to 600°C., from 250 to 550° C., etc.

Embodiment 11

The process defined in any one of the preceding embodiments, furthercomprising a step of contacting a transition metal-ligand complex withan olefin and carbon dioxide (CO₂) to form the metallalactone.

Embodiment 12

A process for producing an α,β-unsaturated carboxylic acid, or a saltthereof, the process comprising:

(I) contacting

-   -   (i) a transition metal-ligand complex;    -   (ii) an olefin;    -   (iii) carbon dioxide (CO₂);    -   (iv) a diluent; and    -   (v) a solid promoter; and

(II) forming the α,β-unsaturated carboxylic acid, or the salt thereof.

Embodiment 13

The process defined in embodiment 11 or 12, wherein the olefin comprisesany suitable olefin or any olefin disclosed herein, e.g. ethylene,propylene, 1-butene, etc.

Embodiment 14

The process defined in any one of embodiments 1-13, wherein theα,β-unsaturated carboxylic acid, or a salt thereof, comprises anysuitable α,β-unsaturated carboxylic acid, or any α,β-unsaturatedcarboxylic acid disclosed herein, or a salt thereof, e.g., acrylic acid,methacrylic acid, 2-ethylacrylic acid, sodium acrylate, magnesiumacrylate, sodium methacrylate, etc.

Embodiment 15

The process defined in any one of embodiments 1-14, wherein the molaryield of the α,β-unsaturated carboxylic acid, or the salt thereof, basedon the metallalactone (or the transition metal-ligand complex) is in anyrange disclosed herein, e.g., at least 5%, at least 10%, at least 20%,from 5% to 95%, from 5% to 90%, from 10% to 95%, from 10% to 90%, from15% to 95%, etc.

Embodiment 16

The process defined in any one of embodiments 1-15, wherein the processfurther comprises a step of isolating the α,β-unsaturated carboxylicacid, or the salt thereof, e.g., using any suitableseparation/purification procedure or any separation/purificationprocedure disclosed herein, e.g., evaporation, distillation,chromatography, etc.

Embodiment 17

The process defined in any one of embodiments 1-16, wherein thecontacting step and/or the forming step is/are conducted at any suitablepressure or at any pressure disclosed herein, e.g., from 5 psig to10,000 psig, from 45 psig to 1000 psig, etc.

Embodiment 18

The process defined in any one of embodiments 1-17, wherein thecontacting step and/or the forming step is/are conducted at any suitabletemperature or at any temperature disclosed herein, e.g., from 0° C. to250° C., from 0° C. to 95° C., from 15° C. to 70° C., etc.

Embodiment 19

The process defined in any one of embodiments 1-18, wherein thecontacting step is conducted at any suitable weight hourly spacevelocity (WHSV) or any WHSV disclosed herein, e.g., from 0.05 to 50,from 1 to 25, from 1 to 5, etc., based on the amount of the solidpromoter.

Embodiment 20

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable basic promoter, or any basic promoterdisclosed herein.

Embodiment 21

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable Lewis acid promoter.

Embodiment 22

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable Bronsted base promoter, or any Bronstedbase promoter disclosed herein.

Embodiment 23

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable Bronsted base and Lewis acid promoter,or any Bronsted base and Lewis acid promoter disclosed herein.

Embodiment 24

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable solid oxide, or any solid oxidedisclosed herein.

Embodiment 25

The process defined in embodiment 24, wherein the solid oxide comprisesAl₂O₃, B₂O₃, BeO, Bi₂O₃, CdO, Co₃O₄, Cr₂O₃, CuO, Fe₂O₃, Ga₂O₃, La₂O₃,Mn₂O₃, MoO₃, Na₂O, NiO, P₂O₅, Sb₂O₅, SiO₂, SnO₂, SrO, ThO₂, TiO₂, V₂O₅,WO₃, Y₂O₃, ZnO, ZrO₂, K₂O, CaO, La₂O₃, or Ce₂O₃, including mixed oxidesthereof, and combinations thereof.

Embodiment 26

The process defined in embodiment 24, wherein the solid oxide comprisessilica, alumina, titania, zirconia, magnesia, boria, calcia, zinc oxide,silica-alumina, silica-coated alumina, silica-titania, silica-zirconia,silica-magnesia, alumina-titania, alumina-zirconia, zinc-aluminate,alumina-boria, silica-boria, aluminum phosphate, aluminophosphate,aluminophosphate-silica, magnesium aluminate, titania-zirconia, or acombination thereof.

Embodiment 27

The process defined in embodiment 24, wherein the solid oxide comprisesmagnesium aluminate, calcium aluminate, zinc aluminate, zirconiumaluminate, sodium aluminate, magnesium zirconium oxide, sodium zirconiumoxide, calcium zirconium oxide, lanthanum chromium oxide, bariumtitanium oxide, or a combination thereof.

Embodiment 28

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises any suitable clay or pillared clay, or any clay orpillared clay disclosed herein.

Embodiment 29

The process defined in embodiment 28, wherein the clay or pillared claycomprises montmorillonite, bentonite, nontronite, hectorite, halloysite,vermiculite, mica, fluoromica, chlorite, sepiolite, attapulgite,palygorskite, illite, saponite, allophone, smectite, kaolinite,pyrophyllite, or a combination thereof.

Embodiment 30

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises silica, alumina, silica-alumina, aluminum phosphate,alumina-boria, silica-magnesia, silica-titania, zirconia, magnesia,magnesium aluminate, sepiolite, titania, palygorskite, montmorillonite,talc, kaolinite, halloysite, pyrophyllite, or a combination thereof.

Embodiment 31

The process defined in any one of embodiments 1-19, wherein the solidpromoter comprises alumina, zirconia, magnesia, magnesium aluminate,sepiolite, or a combination thereof.

Embodiment 32

The process defined in any one of embodiments 1-31, wherein the solidpromoter has any suitable surface area, or a surface area in any rangedisclosed herein, e.g., from 10 to 750 m²/g, from 20 to 500 m²/g, from30 to 350 m²/g, etc.

Embodiment 33

The process defined in any one of embodiments 1-32, wherein the solidpromoter has any suitable pore volume, or a pore volume in any rangedisclosed herein, e.g., from 0.1 to 2.5 mL/g, from 0.1 to 1.5 mL/g, from0.2 to 1.0 mL/g, etc.

Embodiment 34

The process defined in any one of embodiments 1-33, wherein prior tostep (1) or step (I), the solid promoter is calcined at any suitabletemperature, or at a temperature in any range disclosed herein, e.g.from 150° C. to 1000° C., from 200° C. to 750° C., from 300° C. to 600°C., etc.

Embodiment 35

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable non-protic solvent, or any non-protic solventdisclosed herein.

Embodiment 36

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable weakly coordinating or non-coordinating solvent,or any weakly coordinating or non-coordinating solvent disclosed herein.

Embodiment 37

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable carbonyl-containing solvent, or anycarbonyl-containing solvent disclosed herein, e.g., ketones, esters,amides, etc. (e.g., acetone, ethyl acetate, N,N-dimethylformamide,etc.).

Embodiment 38

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable ether solvent, or any ether solvent disclosedherein, e.g., THF, dimethyl ether, diethyl ether, dibutyl ether, etc.

Embodiment 39

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable aromatic hydrocarbon solvent, or any aromatichydrocarbon solvent disclosed herein, e.g., benzene, xylene, toluene,etc.

Embodiment 40

The process defined in any one of embodiments 1-34, wherein the diluentcomprises any suitable halogenated aromatic hydrocarbon solvent, or anyhalogenated aromatic hydrocarbon solvent disclosed herein,chlorobenzene, dichlorobenzene, etc.

Embodiment 41

The process defined in any one of embodiments 1-34, wherein the diluentcomprises THF, 2,5-Me₂THF, methanol, acetone, toluene, chlorobenzene,pyridine, or a combination thereof.

Embodiment 42

The process defined in any one of embodiments 1-41, wherein thetransition metal of the metallalactone (or of the transitionmetal-ligand complex) is a Group 8-11 transition metal.

Embodiment 43

The process defined in any one of embodiments 1-41, wherein thetransition metal of the metallalactone (or of the transitionmetal-ligand complex) is Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, or Au.

Embodiment 44

The process defined in any one of embodiments 1-41, wherein thetransition metal of the metallalactone (or of the transitionmetal-ligand complex) is Ni, Fe, or Rh.

Embodiment 45

The process defined in any one of embodiments 1-41, wherein themetallalactone is a nickelalactone, e.g., any suitable nickelalactone orany nickelalactone disclosed herein.

Embodiment 46

The process defined in any one of embodiments 1-45, wherein the ligandof the metallalactone (or of the transition metal-ligand complex) is anysuitable neutral electron donor group and/or Lewis base, or any neutralelectron donor group and/or Lewis base disclosed herein.

Embodiment 47

The process defined in any one of embodiments 1-45, wherein the ligandof the metallalactone (or of the transition metal-ligand complex) is abidentate ligand.

Embodiment 48

The process defined in any one of embodiments 1-47, wherein the ligandof the metallalactone (or of the transition metal-ligand complex)comprises at least one of a nitrogen, phosphorus, sulfur, or oxygenheteroatom.

Embodiment 49

The process defined in any one of embodiments 1-47, wherein the ligandof the metallalactone (or of the transition metal-ligand complex) is anysuitable carbene group or any carbene group disclosed herein.

Embodiment 50

The process defined in any one of embodiments 1-47, wherein themetallalactone, ligand, or transition metal-ligand complex is anysuitable metallalactone, ligand, or transition metal-ligand complex, oris any metallalactone, ligand, or transition metal-ligand complexdisclosed herein.

We claim:
 1. A process for performing a metallalactone eliminationreaction, the process comprising: (1) forming a reaction mixtureconsisting essentially of (a) a metallalactone; (b) a diluent; and (c) asolid promoter selected from the group consisting of alumina, zirconia,magnesia, magnesium aluminate, and sepiolite, or a combination thereof;and (2) forming an α,β-unsaturated carboxylic acid, or a salt thereof;wherein the molar yield of the α,β-unsaturated carboxylic acid, or thesalt thereof, based on the metallalactone, is at least 5%.
 2. Theprocess of claim 1, wherein: the α,β-unsaturated carboxylic acidcomprises acrylic acid.
 3. The process of claim 1, wherein in step (1),the metallalactone and the diluent contact a fixed bed of the solidpromoter.
 4. The process of claim 1, wherein the metallalactone is anickelalactone.
 5. A process for producing an α,β-unsaturated carboxylicacid, or a salt thereof, the process comprising: (1) contacting (a) ametallalactone; (b) a diluent; and (c) a solid oxide; (2) forming anadduct of an α,β-unsaturated carboxylic acid adsorbed onto the solidoxide; and (3) contacting the adduct adsorbed onto the solid oxide withan acid to produce the α,β-unsaturated carboxylic acid, or the saltthereof.
 6. The process of claim 5, wherein: the α,β-unsaturatedcarboxylic acid, or the salt thereof, comprises acrylic acid,methacrylic acid, 2-ethylacrylic acid, sodium acrylate, magnesiumacrylate, sodium methacrylate, or a combination thereof; and the molaryield of the α,β-unsaturated carboxylic acid, or the salt thereof, basedon the metallalactone, is at least 5%.
 7. The process of claim 5,wherein: the metallalactone is a nickelalactone; the solid oxide is aBronsted base and a Lewis acid; and the α,β-unsaturated carboxylic acidcomprises acrylic acid.
 8. The process of claim 5, wherein: the solidoxide comprises silica, alumina, titania, zirconia, magnesia, boria,calcia, zinc oxide, silica-alumina, silica-coated alumina,silica-titania, silica-zirconia, silica-magnesia, alumina-titania,alumina-zirconia, zinc-aluminate, alumina-boria, silica-boria, aluminumphosphate, aluminophosphate, aluminophosphate-silica, magnesiumaluminate, titania-zirconia, or a combination thereof; and the molaryield of the α,β-unsaturated carboxylic acid, or the salt thereof, basedon the metallalactone, is at least 5%.
 9. The process of claim 5,wherein: the solid oxide comprises magnesium aluminate, calciumaluminate, zinc aluminate, zirconium aluminate, sodium aluminate,magnesium zirconium oxide, sodium zirconium oxide, calcium zirconiumoxide, lanthanum chromium oxide, barium titanium oxide, or a combinationthereof; and the molar yield of the α,β-unsaturated carboxylic acid, orthe salt thereof, based on the metallalactone, is at least 5%.
 10. Theprocess of claim 5, wherein: the molar yield of the α,β-unsaturatedcarboxylic acid, or the salt thereof, based on the metallalactone, is atleast 5%; the metallalactone is a nickelalactone; and theα,β-unsaturated carboxylic acid comprises acrylic acid.
 11. The processof claim 5, wherein: the solid oxide comprises alumina, zirconia,magnesia, magnesium aluminate, sepiolite, or a combination thereof; andthe molar yield of the α,β-unsaturated carboxylic acid, or the saltthereof, based on the metallalactone, is at least 10%.
 12. The processof claim 5, wherein the metallalactone comprises:

or a combination thereof, wherein Cy is cyclohexyl and ^(t)Bu istert-butyl.
 13. A process for producing an α,β-unsaturated carboxylicacid, or a salt thereof, the process comprising: (I) forming a reactionmixture consisting essentially of (i) a transition metal-ligand complex;(ii) an olefin; (iii) carbon dioxide (CO2); (iv) a diluent; and (v) asolid promoter selected from the group consisting of magnesiumaluminate, calcium aluminate, zinc aluminate, zirconium aluminate,sodium aluminate, magnesium zirconium oxide, sodium zirconium oxide,calcium zirconium oxide, lanthanum chromium oxide, barium titaniumoxide, alumina, zirconia, magnesia, magnesium aluminate, and sepiolite,or a combination thereof; and (II) forming the α,β-unsaturatedcarboxylic acid, or the salt thereof; wherein the molar yield of theα,β-unsaturated carboxylic acid, or the salt thereof, based on thetransition metal-ligand complex, is at least 5%.
 14. The process ofclaim 13, wherein: the olefin comprises ethylene; and theα,β-unsaturated carboxylic acid comprises acrylic acid.
 15. The processof claim 13, wherein the transition metal of the transition metal-ligandcomplex is a Group 8-11 transition metal, and the ligand of thetransition metal-ligand complex is a neutral electron donor group orLewis base.
 16. The process of claim 13, wherein the solid promoter is aLewis acid.
 17. The process of claim 13, wherein the solid promoter ismagnesium aluminate, calcium aluminate, zinc aluminate, zirconiumaluminate, sodium aluminate, magnesium zirconium oxide, sodium zirconiumoxide, calcium zirconium oxide, lanthanum chromium oxide, bariumtitanium oxide, or a combination thereof.
 18. The process of claim 13,wherein the solid promoter is alumina, zirconia, magnesia, magnesiumaluminate, sepiolite, or a combination thereof.
 19. The process of claim13, wherein in step (I), the transition metal-ligand complex, theolefin, the carbon dioxide, and the diluent contact a fixed bed of thesolid promoter.